The goal of this research proposal is to test the hypothesis that polycyclic aromatic hydrocarbons (PAHs) are toxic to the male reproductive system. It is hypothesized that PAHs may act as anti-estrogens, estrogens or a direct toxicant to the cells of the seminiferous epithelium. SPECIFIC AIM A: To identify and quantify cellular disruption of the seminiferous epithelium in sexually mature male rats due to exposure of PAHs. The hypothesis is that PAHs cause testicular cytoarchitectural disruption perturbing final development of mature spermatozoa. Particular subclasses of male germ cells will be examined to assess the damage from the histological preparations by using morphometric analysis. The study will include enzyme and cell surface marker analysis which may possibly be altered due to PAH toxicity. SPECIFIC AIM B: To determine in sexually mature males the manner in which PAHs influence sperm production, sperm storage, and sperm morphology. The hypothesis is that PAHs alter testicular, epididymal and male accessory sex gland weights and histology, and in turn, suppress testicular sperm production and storage. Quantitative microscopical analysis will be done on testicular and epididymal sperm using a hemocytometer. Epididymal sperm morphology will also be evaluated. SPECIFIC AIM C: To determine the effects of PAHs exposure on germ cell-Sertoli cell adhesion using functional bioassays. The hypothesis is that PAHs alter cell adhesion molecules and thus, Sertoli cell-germ cell interaction will be ineffective. An adherent cell analysis and sorting laser scanning cytometry will measure Sertoli cell-germ cell adhesion. SPECIFIC AIM D: To determine the effects of PAHs exposure on specific intercellular junctions of the seminiferous epithelium. The hypothesis is that PAHs exposure disrupts the formation of intercellular junctions between adjacent Sertoli cells. Tight junctions and gap junctions will be examined. Junctions will be examined both in vivo and in vitro Light microscopy using confocal analysis, and ultrastructural observations using tracer studies will be included. Western blotting and quantitative ELISA methods will be used with antibodies specific for tight junctions and gap junctions. SPECIFIC AIM E: To determine if PAH-induced toxic effect is mediated by estrogenicity of the PAHs. The hypothesis is that PAH exposure results from an estrogen receptor mediated mechanism. The dose response relationship between the proliferation of MCF- 7 cells and the amount of various PAHs to which the cells are exposed will be established. Estradiol-17beta will be used as standard for comparison . Results of these investigations will provide insight into our understanding of the manner in which the PAH environmental pollutants act to interfere with the male reproductive system.